module.exports = {
  _store: Object.create(null),
  setItem: function (key, value) {
    this._store[key] = value;
  },
  getItem: function (key) {
    return key in this._store ? this._store[key] : null;
  },
  removeItem: function (key) {
    if (key in this._store) {
      delete this._store[key];
    }
  },
  key: function (i) {
    return Object.keys(this._store)[i];
  },
  get length () {
    return Object.keys(this._store).length;
  }
};
